The objective of the proposed research is to measure the parameters which describe power deposition and heat dissipation when radiofrequency heating is used to induce local and regional hyperthermia in cancer therapy. The electrical conductivity and dielectric permissivity will be measured with a small hypodermic needle probe which can be inserted into the tumor and surrounding normal tissue. Similarly, the effective thermal conductivity of the tissue which is dependent upon the blood flow as well as intrinsic conductivity will be measured with a thermistor probe. Measurements are to be made throughout the tumor region prior to treatment, immediately following treatment, and, when possible, several days later at clinical follow-up sessions. The information will be used principally for treatment planning and subsequent numerical analysis using appropriate forms of the bio-heat equation. The data also will be analyzed for effects due to histological changes resulting from therapy. Tumors in both animals and humans will be studied.